Mercedes-Benz's Citaro 'Zero Emissions' Bus

The Mercedes Benz Citaro Fuel Cell Bus (FCELL or F-CELL) is getting closer to becoming a full scale commercial product for Daimler AG. The excellent aspect about this bus is that it produces zero emissions with pure water being the exhaust product. The Citaro can carry up to 70 passengers and it runs on compressed hydrogen. Daimler's Mercedes-Benz has been working on the hydrogen Fuel Cell Bus Project since 2003 and has conducted long-term trials in various major city centres worldwide. Daimler is currently working on their second generation Citaro fuel cell bus and this is expected to be completed by mid 2009.

The Citaro's hydrogen fuel cell works by converting hydrogen into electricity through a proton exchange membrane (PEM), and the electricity is used to drive the Citaro's 200 kW electric motor. The compressed hydrogen gas cylinders and the hydrogen fuel cell engine are located on the roof of the vehicle. The Mercedes-Benz Citaro Hydrogen Fuel Cell Bus has a top speed of 80 km/h (50 mph) and a range of approximately 200 km (124 miles).

There are arguments that hydrogen itself is an inefficient fuel to produce, because it requires large amounts of energy to convert water into hydrogen gas; however, hydrogen fuel cells are very efficient at producing electricity from hydrogen gas. The beauty of fleets of hydrogen fuel cell buses is that each bus can replace as many as 70 cars travelling into a major city and from that perspective there is really no argument against them. The pure benefit of a hydrogen fuel cell's zero emissions combined with the efficient means of transporting many people helps support the utilisation of hydrogen in this instance as an energy source and part of the energy solution.